Many cryogenic refrigerators, such as Stirling refrigerators and pulse tubes, are driven by a reciprocating pressure wave. Conventionally, the pressure waves are generated by clearance gap pistons that are driven by linear motors, although these are costly technologies. More recently, diaphragm based pressure wave generators have been proposed. These diaphragm pressure wave generators use low cost diaphragms manipulated in a reciprocating manner to generate pressure waves in an efficient and cost effective manner. A significant benefit of diaphragm pressure wave generators for cryogenic refrigerator systems is that the diaphragms separate the clean gas environment required by the cryogenic cooler from the drive system that reciprocates the diaphragms. This allows cheaper driving components, such as standard rotary and crank mechanisms, to be used in the pressure wave generator.
By way of example, international PCT patent application publication WO 2006/112741 proposes a diaphragm pressure wave generator that comprises, in one form, a pair of opposed diaphragms that are moved in a reciprocating motion by a reciprocating drive piston to create pressure waves.
In this specification where reference has been made to patent specifications, other external documents, or other sources of information, this is generally for the purpose of providing a context for discussing the features of the invention. Unless specifically stated otherwise, reference to such external documents is not to be construed as an admission that such documents, or such sources of information, in any jurisdiction, are prior art, or form part of the common general knowledge in the art.
It is an object of the present invention to provide an improved drive system for diaphragm pressure wave generators, or to at least provide the public with a useful choice.